The present invention relates to mammography, and more particularly, to means for compressing and retaining breast tissue in preparation for imaging analysis.
Early detection of breast cancer relies on high quality mammography. In order to achieve this in the prior art, the breast is compressed between an x-ray detector or imager and a rigid compression plate. Compression of the breast tissue is necessary to retain the tissue and to spread the internal structures of the breast, to reduce motion of the breast, to reduce x-ray dose required of thicker tissue, and to position the breast correctly over the detector so that as much tissue as possible can be imaged at one time. In addition, forcing the breast tissues closer to the detector improves the geometric sharpness of the image obtained and evens out the exposure.
Prior mammography systems have generally included compression devices. For example, in U.S. Pat. No. 3,824,397, a plastic sheet has been used to applied pressure to breast tissue. However, uniform pressure over the entire breast cannot be obtained with this device. U.S. Pat. No. 4,090,084 provides a mounted pressure plate for the application of uniform pressure. However, compression with a flat plate can result in the breast tissue being squeezed out of the x-ray field back towards the chest wall. The result is that tissue which may contain a tumor is not imaged. Another device is described in U.S. Pat. No. 3,971,950 wherein a compression paddle with a curved surface is used to exert a variable force and is adjustable in a plurality of directions so an image of a selective view may be obtained. However, this device does not provide for the imaging of tissue pushed out of the scope of the detection device at the chest wall.
Accordingly, the object of the present invention is to provide a support/compression device for mammography which prevents the slippage of breast tissue from the field of view of the x-ray detector or imager.
Another object of the invention is to provide a compression device which enables the application of uniform pressure to the entire breast without allowing the escape of breast tissue outside of the pressure field.
Yet another object is to enlarge the field of view of an x-ray detector to cover as much of an entire breast as possible.
These and other objects of the invention will be apparent from the description, drawing, and claims that follow.